Compound Corners - Excerpt
This is an extract from a chapter in Racelogic’s ebook discussing Advanced Circuit Driving Techniques with professional racing drivers and instructors. To download the ebook (and receive further chapters in the future) scroll to the bottom of this page and fill in your email address.
Definition Compound cornerA series of corners, close enough such that the car is always turning and never travelling in a straight line. |
The following data was taken from a Funcup race at Misano in 2009:
Nigel Greensall - ‘It is a common mistake to treat compound corners as two separate items, whereas they should be tackled as one section, with sacrifices being made in the first corner to gain maximum exit speed. It often seems counter-intuitive not to maximise the speed through the first corner, but the end result is often a faster lap.
There are many examples, but let’s take Misano Circuit which is shown on the left, Turns 12 and 13 which consists of a shallow right hand corner followed by a sharper right hand corner.
On first inspection you may naturally assume that you have to clip apexes of both Turns 12 and 13 to get the best lap-time.
However, there are many other ways to take these corners and I have found that the quickest for me is to almost ignore Turn 12 by missing the apex completely, and set yourself up for a nice wide entry into Turn 13, which seems a little odd at first.
To see this line in action, have a look at the image on the left, which shows my preferred line in red, and my team mates line in blue.
The red line misses the apex of Turn 12 by almost 2m, but maintains the same apex speed of 105mph as the blue line which clips the apex.
Interestingly, through Turn 12 you are not quite on the limit of grip (a peak of 0.85G), so you can experiment with your lines through here without losing any speed.
This wider line is also slightly shorter, which also gives a small advantage.
The screenshot on the right shows the apex point of Turn 12, where both approaches have the same speed, 105mph.
It is after this point where the reason for this wider line becomes clearer.
If you treat Turn 12 as a conventional corner and clip the apex, you cannot get far enough across to use the whole width of the track into Turn 13.
By running wide in Turn 12, you can get much further over to the left for the entry into Turn 13 allowing more speed to be carried around the corner.
Using more screenshots from the in-car video, you can see just how much closer to the edge of the track (just before Turn 13) I could go, whilst carrying 7mph more speed:
If we look at the Apex speeds of the second turn using Circuit Tools software, the gain in speed is even greater:
In this screenshot you can see that the wider line allows me to carry 11mph more at the Apex, the upper graph is the speed, and the lower graph is the Delta-T or time difference between the two laps.
The analysis software showed a total gain of 0.67s in this section, which was very simple to achieve, just by taking a slightly wider line through Turn 12, which is very easy to do!’
We now zip 2700 miles across to the Dubai Autodrome in an Aston Martin GT4.
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